Environmental exposure of primary care personnel to ribavirin aerosol when supervising treatment of infants with respiratory syncytial virus infections

Review of the Safety, Efficacy and Tolerability of Palivizumab in the Prevention of Severe Respiratory Syncytial Virus (RSV) Disease

Respiratory Syncytial Virus (RSV) is a major global cause of childhood morbidity and mortality. Palivizumab, a monoclonal antibody that provides passive immunity against RSV, is currently licensed for prophylactic use in specific "high-risk" populations, including congenital heart disease, bronchopulmonary dysplasia and prematurity. Available research suggests palivizumab use in these high-risk populations can lead to a reduction in RSV-related hospitalization. However, palivizumab has not been demonstrated to reduce mortality, adverse events or length of hospital stay related to RSV. In this article, we review the management of RSV, indications for palivizumab prophylaxis, the safety, cost-effectiveness and efficacy of this preventative medication, and emerging therapeutics that could revolutionize future prevention of this significant pathogen.

Novel insights into human respiratory syncytial virus-host factor interactions through integrated proteomics and transcriptomics analysis

The lack of vaccine and limited antiviral options against respiratory syncytial virus (RSV) highlights the need for novel therapeutic strategies. One alternative is to develop drugs that target host factors required for viral replication. Several microarray and proteomics studies had been published to identify possible host factors that are affected during RSV replication. In order to obtain a comprehensive understanding of RSV-host interaction, we integrated available proteome and transcriptome datasets and used it to construct a virus-host interaction network. Then, we interrogated the network to identify host factors that are targeted by the virus and we searched for drugs from the DrugBank database that interact with these host factors, which may have potential applications in repositioning for future treatment options of RSV infection.

Acute bronchiolitis

Bronchiolitis is the most common lower respiratory tract infection to affect infants and toddlers. High-risk patients include infants younger than 3 months, premature infants, children with immunodeficiency, children with underlying cardiopulmonary or neuromuscular disease, or infants prone to apnea, severe respiratory distress, and respiratory failure. Bronchiolitis is a self-limited disease in healthy infants and children. Treatment is usually symptomatic, and the goal of therapy is to maintain adequate oxygenation and hydration. Use of a high-flow nasal cannula is becoming common for children with severe bronchiolitis.

Identification and management of severe respiratory syncytial virus

PURPOSE

Identifying children at risk for severe respiratory syncytial virus (RSV) so that the most appropriate management strategies can be implemented, thereby reducing the morbidity associated with this disease, is discussed.

SUMMARY

RSV infection is associated with a variety of clinical manifestations, ranging from mild cold-like symptoms to more severe disease. The majority of infants infected with RSV develop mild upper respiratory tract disease during their initial RSV infection. However, more severe RSV disease can occur when the lower respiratory tract becomes involved, with symptoms escalating to include significant wheezing and chest-wall retractions, as well as cyanosis and tachypnea in the most severe cases. Extrapulmonary manifestations of RSV disease also have been observed, such as sepsis-like syndrome and arrhythmias. Factors that increase the risk of acquiring RSV infection have been identified, along with factors that increase the risk of severe RSV disease. The American Academy of Pediatrics (AAP) recommends that clinicians assess risk factors for severe disease when making decisions regarding evaluation and management of children with bronchiolitis. There is currently no curative treatment for RSV infection, and management primarily involves the treatment of specific symptoms. The AAP developed clinical practice guidelines to provide an evidence-based approach to the diagnosis and management of bronchiolitis in children aged one month to two years, with detailed recommendations on which therapies are appropriate for children with more severe RSV disease.

CONCLUSION

The AAP developed specific guidelines for the management of RSV bronchiolitis; however, treatment is primarily supportive and has been shown to be suboptimal in many patients. Because of the limitations associated with the management of RSV disease, prevention remains of paramount importance, especially in patients at high risk for severe disease.

Diagnosis and management of bronchiolitis

Bronchiolitis is a disorder most commonly caused in infants by viral lower respiratory tract infection. It is the most common lower respiratory infection in this age group. It is characterized by acute inflammation, edema, and necrosis of epithelial cells lining small airways, increased mucus production, and bronchospasm. The American Academy of Pediatrics convened a committee composed of primary care physicians and specialists in the fields of pulmonology, infectious disease, emergency medicine, epidemiology, and medical informatics. The committee partnered with the Agency for Healthcare Research and Quality and the RTI International-University of North Carolina Evidence-Based Practice Center to develop a comprehensive review of the evidence-based literature related to the diagnosis, management, and prevention of bronchiolitis. The resulting evidence report and other sources of data were used to formulate clinical practice guideline recommendations. This guideline addresses the diagnosis of bronchiolitis as well as various therapeutic interventions including bronchodilators, corticosteroids, antiviral and antibacterial agents, hydration, chest physiotherapy, and oxygen. Recommendations are made for prevention of respiratory syncytial virus infection with palivizumab and the control of nosocomial spread of infection. Decisions were made on the basis of a systematic grading of the quality of evidence and strength of recommendation. The clinical practice guideline underwent comprehensive peer review before it was approved by the American Academy of Pediatrics. This clinical practice guideline is not intended as a sole source of guidance in the management of children with bronchiolitis. Rather, it is intended to assist clinicians in decision-making. It is not intended to replace clinical judgment or establish a protocol for the care of all children with this condition. These recommendations may not provide the only appropriate approach to the management of children with bronchiolitis.

Pregnancy outcome after exposure to injectable ribavirin during embryogenesis

We describe normal pregnancy outcome in a case of first trimester exposure to injectable ribavirin in a 36-year-old pregnant woman who received three intramuscular injections of ribavirin for suspected SARS. She delivered at 40 weeks of gestation a healthy baby girl. In pediatric follow up at 8 month of age, physical examination and neurodevelopmental milestones were normal.

Antiviral therapies in children: has their time arrived?

The increase in the number and classes of antiviral agents that has occurred since the 1980s is remarkable. The rapid expansion in therapeutic options for previously untreatable illnesses challenges clinicians to gain familiarity and experience with these new drugs, especially with regard to their use in children. This article describes the clinical utilities, pharmacokinetics, and adverse effects of these new drugs to empower practitioners to use them appropriately.

Ribavirin dose modification based on renal function is necessary to reduce hemolysis in liver transplant patients with hepatitis C virus infection

Hepatitis C virus (HCV) is currently the most common etiology for liver transplantation (LTx) in the United States. A significant number of patients develop recurrent HCV after LTx. Although there is no completely satisfactory treatment for recurrent HCV, a combination of interferon-alpha (INF) and ribavirin remains the most widely used. Ribavirin is eliminated through the kidneys and tends to accumulate in the presence of renal dysfunction. The primary side effect of ribavirin is hemolysis. The goal of the present study was to correlate the incidence of hemolysis with renal function in LTx patients with recurrent HCV who were being treated with ribavirin. The incidence of hemolysis and the renal function were examined in 72 liver transplant patients (58 male and 14 female patients) with recurrent HCV receiving INF (3 million units, three times per week) and ribavirin (initial dose of 400 mg twice daily). Patients were grouped according to the decrease in the percentage of hematocrit after the introduction of ribavirin, with their baseline serum creatinine and creatinine clearance calculated using the Cockcroft-Gault formula. The decrease in the percentage of hematocrit after ribavirin treatment was also examined with respect to creatinine clearance as a continuous variable. In addition, for purposes of presentation, patients were analyzed in three groups: creatinine clearance of >/= 70 mL/min (group A), creatinine clearance < 70 mL/min and >/= 40 mL/min (group B), and creatinine clearance < 40 mL/min (group C). Forty-five (62.5%) patients experienced a decrease in hematocrit (Hct) >/=15% after starting INF and ribavirin. The mean serum creatinine was 1.3 +/- 0.5 mg/dL (median, 1.3) in this group, and the mean calculated creatinine clearance was 71 +/- 29 mL/min (median, 66.47). In the 27 patients who did not show a significant decrease (< 15%) in hematocrit, the mean serum creatinine was 1.1 +/- 0.3 mg/dL (median, 1.0) and the mean creatinine clearance was 95 +/- 39 (median, 96) mL/min (P =.018). On continuous variable of calculated creatinine clearance, there was a trend in the decrease in hematocrit after ribavirin treatment compared with pretreatment (P =.09). However, the rate of hemolysis was significantly different in group A (53.7%), group B (70.8%), and group C (100%) (P =.042). Patients on INF and ribavirin therapy who experienced hemolysis had significantly higher serum creatinine levels and lower creatinine clearances compared with those who did not have hemolysis. The incidence of hemolysis was significantly associated with higher serum creatinine and decreased creatinine clearance. Because ribavirin is eliminated by the kidneys, this observation points to the need for adjustments in the dose of this agent in LTx patients, who tend to have some degree of renal dysfunction, to reduce the incidence of hemolysis. Further pharmacokinetic studies of ribavirin in LTx patients with varying degrees of renal function may allow the development of an algorithm for the safer use of ribavirin in HCV-positive LTx patients.

Parainfluenza virus type 3 infections in a hematology unit

Parainfluenza virus type 3 (PIV3) is associated with a high mortality rate in BMT recipients with lower respiratory tract infections. We describe nine patients with hematological malignancies (five having undergone either allogeneic or autologous stem cell transplantation) identified as having PIV3 infection during a 2-month period in a Hematology Unit. Four patients with infiltrates on chest radiograph received intravenous ribavirin therapy; all survived. The infection was community-acquired in two patients, while nosocomial origin of the disease was evident, or presumed, in the remaining seven. The policy implemented to control the spread of PIV3 was as follows: (1) nasopharyngeal samples for antigen detection were obtained from all patients presenting with respiratory symptoms; (2) all diagnosed (or suspected) PIV3-positive hematological patients were nursed following contact isolation precautions, preferably in the Infectious Diseases Unit; and (3) staff were given further education on hospital hygiene. Our experience shows that it may be possible to avoid mortality for PIV3 lower respiratory tract infection in immunocompromised patients by early commencement of intravenous ribavirin. It is also possible, even without closing the ward, to contain nosocomial spread of PIV3 by implementing systematic nasopharyngeal sampling for rapid diagnostics, and by strict adherence to cohorting and contact isolation precautions.

[Is the use of ribavirin aerosols in respiratory syncytial virus infections justified? Clinical and economic evaluation]

The controversy about the use of ribavirin aerosol for children at risk (cardiopathy, pneumopathy, premature and immunodeficient patients), in case of respiratory syncytial virus (RSV) infection, led us to stop its prescription in 1993 and study prospectively the patients admitted during the following winters.

METHODS

Criterias of inclusion for this study were those of the Committee on Infectious Diseases of the American Academy of Pediatrics concerning the use of ribavirin aerosol. Two cohorts of patients were studied: the first group included treated patients (ribavirin group: n = 22, ribavirin and support treatment: salbutamol aerosols, respiratory physiotherapy and oxygen-therapy; winters 1989-1990 to 1992-1993); the second group included patients with support treatment only (control group: n = 22; winters 1993-1994 and 1994-1995).

RESULTS

The clinical gravity score at admission (4.55 vs 5.23, P = 0.46) and the risk factor scores (3.05 vs 3.27, P = 0.69) of the two groups were identical. Results showed that the children of the ribavirin group stayed much longer in hospital (14.2 vs 8.2 days, P = 0.002) and in the intensive care unit (7.2 vs 0.2 days, P < 0.001) than those of the control group. More support treatment was necessary for the ribavirin group as regard respiratory physiotherapy (3.8 vs 2.7 sessions a day, P = 0.026), the duration of oxygen-therapy (7.3 vs 3.7 days, P = 0.030) and the number of children requiring respiratory assistance (4 vs 0 children, P = 0.116). Administration of ribavirin aerosols (480 US$ a dose) and the way in which such treatment was carried out meant high daily costs for the ribavirin group (1,076 vs 604 US$, P < 0.001). As hospitalization was longer for children treated with ribavirin, the global cost was therefore much higher (15,552 vs 5,156 US$, P < 0.001).

CONCLUSION

The antiviral effect of ribavirin is undeniable. However ribavirin is known to be the cause of severe bronchospasms (two cases in our study) and can also cause moderate and long term bronchospasms, aggravating therefore the clinical evolution of the disease. Our experience shows that administration of ribavirin aerosols in case of RSV infection of inferior respiratory airways seems not to be justified.

Prevention and treatment of respiratory syncytial virus and parainfluenza viruses in immunocompromised patients

Immunocompromised patients are vulnerable to severe infections due to respiratory syncytial virus (RSV) and parainfluenza viruses (PIV), and therefore prevention and treatment strategies must be considered. The prevention of RSV disease with high-titer RSV-specific immune globulin has been documented in very young children but has not been systematically studied in high-risk adults. Vaccines against RSV and PIV are under development, but their use in immunocompromised patients is problematic. Ribavirin aerosol therapy is licensed for the treatment of RSV in pediatric patients and has also been used to treat RSV disease in adults and PIV disease in severely immunocompromised children and adults. Uncontrolled trials show that early therapy with ribavirin aerosol may be beneficial, but treatment of pneumonia in patients with respiratory failure is rarely successful. Other potential treatments for RSV or PIV disease include high-dose, short-duration ribavirin therapy; combined immunoglobulin and ribavirin therapy; polyclonal and monoclonal antibodies; and, potentially, immunomodulators.

Phase I study of intravenous ribavirin treatment of respiratory syncytial virus pneumonia after marrow transplantation

Respiratory syncytial virus (RSV) pneumonia in marrow transplant recipients is associated with significant mortality. Ribavirin is a nucleoside analog with activity against RSV and in its aerosolized formulation is the only drug approved for treatment of RSV pneumonia in the United States. The clinical use of aerosolized ribavirin has been limited by caregivers' concerns about drug exposure and potential teratogenic effects. Since there is lack of proven efficacy and safety of the aerosolized ribavirin in this setting, we performed a phase I study of intravenous ribavirin treatment. Between November 1993 and May 1994, 10 patients with clinically significant RSV pneumonia at the Fred Hutchinson Cancer Research Center were enrolled. Only 2 of the 10 survived (20%; 95% CI, 3-56). Two of the 10 patients developed acute hemolysis that necessitated discontinuation of the medication. In conclusion, treatment of marrow transplant recipients with RSV pneumonia with intravenous ribavirin did not improve mortality compared with historical controls treated with the aerosolized drug.

Health care worker exposure to aerosolized ribavirin: biological and air monitoring

Aerosolized ribavirin is administered frequently to treat severe respiratory syncytial virus infections. The drug's potential reproductive effects in occupationally exposed workers remains a concern among health care workers. In this evaluation, we measured urinary ribavirin concentrations in occupationally exposed health care workers. Ribavirin was detected in 16 of 26 (62%) post-work-shift urine samples that had been provided by nurses, and in five of 22 (23%) post-work-shift urine samples that had been provided by respiratory therapists (range, < 0.01 to 0.22 mumol/L). We also measured airborne ribavirin concentrations in the personal breathing zones of nurses. Ventilators and other administration units that were enclosed by an aerosol containment tent produced significantly lower airborne ribavirin exposures than administration units without a containment tent did (range, < 2.5 to 78 micrograms/m3). On the basis of this and other evaluations of airborne ribavirin concentrations, we recommend using aerosol containment systems with all types of ribavirin administration units except mechanical ventilators.

High-dose, short-duration ribavirin aerosol therapy compared with standard ribavirin therapy in children with suspected respiratory syncytial virus infection

Children with suspected respiratory syncytial virus infection were examined prospectively in a randomized evaluation of standard ribavirin aerosol therapy (6 gm/300 ml water for 18 hours daily) compared with high-dose, short-duration ribavirin aerosol therapy (6 gm/100 ml water given for a period of 2 hours three times a day) by means of an oxygen hood (n = 20) or a ventilator (n = 12). Viral shedding was quantitated daily; clinical observations were recorded daily by 2 physicians aware and one unaware of treatment assignments. Study characteristics evaluated at entry were not significantly different in the high-dose and the standard-dose groups. Viral titers and clinical scores decreased similarly in both groups during the study; pulmonary function test results were also similar at discharge in children not receiving mechanical ventilation. Potential complications related to aerosol therapy were noted in three patients (one hood patient who was receiving standard therapy; two patients with an endotracheal tube in place who were receiving high-dose therapy); substantial crystallization was noted in the tubing of the patients undergoing intubation and receiving high-dose therapy. Environmental sampling revealed that ribavirin was nearly undetectable near patients supported by mechanical ventilation who were receiving either form of therapy, and was significantly decreased on a daily basis in patients without an endotracheal tube who were receiving high-dose therapy compared with those receiving standard therapy. The effects of high-dose, short-duration aerosol ribavirin therapy were similar to those of standard-dose therapy in our study patients and resulted in a decreased release of ribavirin into the room of patients receiving therapy by means of an oxygen hood.

Ribavirin treatment for juvenile respiratory papillomatosis

Juvenile respiratory papillomatosis involving the tracheo-bronchial tree imposes a significant management problem and is sometimes life threatening. The mainstay of treatment is repeated vapourization with a CO2 laser. To date, adjunctive medical treatments have been of limited value. A tracheostomized child with extensive laryngo-tracheo-bronchial papillomatosis who has required bronchoscopic lasering at two-weekly intervals for three years was treated with ribavirin, a broad spectrum anti-viral agent. The drug was administered in nebulized form using a small particle aerosol generator (S.P.A.G.) to the lower respiratory tract (6 gm/150 ml over nine hours) on three consecutive nights every two weeks over seven weeks and also administered orally (15 mg/kg/day). Endoscopic assessments were made every two weeks. At 14 days the papillomata were regressing and far less lasering was required. No further lasering was required up to 56 days. One month after stopping the ribavirin, however, a few sessile papillomata in the tracheo-bronchial tree had recurred and were treated with the laser. No adverse reactions were encountered. During the treatment period there was a significant reduction in the frequency of therapeutic endoscopies. This promising response requires further evaluation to define the role of ribavirin in the treatment of juvenile respiratory papillomatosis.

High-dose, short-duration ribavirin aerosol therapy in children with suspected respiratory syncytial virus infection

Nine children (aged 6 weeks to 7 years) with suspected respiratory syncytial virus infection received aerosal treatment with ribavirin, 60 mg/ml for 2-hour periods three times daily for up to 5 days. Five children received treatment via an endotracheal tube and four via an oxygen hood. Blood samples (3 to 17 per patient) and respiratory secretions (4 to 23 per patient) were assayed for ribavirin with reverse-phase high-performance liquid chromatography. Ribavirin triphosphate in erythrocytes was determined by ion-exchange high-performance liquid chromatography. The mean (+/- SD) peak ribavirin level after the first dose was 1725 +/- 2179 mumol/L in secretions and 3.8 +/- 2.6 mumol/L in plasma. Ribavirin in the secretions was rapidly cleared, with a mean (+/- SD), half-life of 1.9 +/- 0.8 hours. Plasma ribavirin increased with treatments to reach a steady state of 5 to 10 mumol/L. Mean peak ribavirin triphosphate levels were 15- to 300-fold higher than plasma ribavirin levels by the end of therapy. More than 98% reduction of viral load without the emergence of resistant virus was noted on day 3 of therapy. High-dose treatment was compatible with the aerosol equipment routinely used (small-particle aerosol generator, model 2-6000) for ribavirin administration and with ventilators. High-dose, short-duration ribavirin therapy was well tolerated by all patients, permitted easier accessibility for patient care, and may result in less environmental exposure of health care workers.

What is the clinical role of aerosolized ribavirin?

Aerosolized ribavirin is the first approved agent for the treatment of respiratory syncytial virus (RSV) infection. However, the clinical use of ribavirin is controversial. Although ribavirin-treated patients appear to be subjectively improved, the benefit in terms of decreased morbidity and mortality is not well established. Furthermore, the drug has been found to be teratogenic, carcinogenic, and mutagenic, depending upon the scientific model. Because of its unique mode of administration, environmental exposure of healthcare personnel and other patients may occur. Although administration in mechanically ventilated patients decreases the amount of ribavirin liberated into the atmosphere, the drug crystallizes in the endotracheal tube, occasionally resulting in reduced ventilation. The lack of data documenting efficacy and the above environmental concerns result in difficult decisions for hospitals. Further studies are necessary to clarify the value and safety of ribavirin in the treatment of RSV infection.

Exposure of health care workers to ribavirin during therapy for respiratory syncytial virus infections

Health care workers (HCW) are exposed to ribavirin aerosol during therapy of infants with respiratory syncytial virus infections. To assess the degree of HCW exposure, we analyzed air samples from patient rooms and HCW personal breathing zones during ribavirin aerosol delivery by ventilator (two samples), oxygen hood (two samples), and a new vacuum exhaust hood (four samples). HCW exposure to ribavirin during aerosol delivery by ventilator or vacuum exhaust hood system was substantially lower than HCW exposure during aerosol delivery by oxygen hood in rooms with adequate ventilation.

Evaluation of exposure of health care personnel to ribavirin

Reports that ribavirin was teratogenic in animals raised concerns of female health care personnel about possible occupational exposure during the care of infants having respiratory syncytial virus infections. Under simulated operational conditions, experiments were conducted to measure ribavirin residues in room air, in surface wipe samples, and in personal sampling devices worn by volunteers. There was exposure to a dispersible dust, presumably dried ribavirin, deposited inside the croupette or hood and on the bedding. Based on personal sampler data, it was estimated that, in a 12-h shift, the primary health care individual could inhale 2.4-9.1 micrograms ribavirin/kg bw.d. Recommendations to reduce the exposure of staff included the wearing of appropriate surgical gloves and a NIOSH-approved disposable respirator for dusts and mists while attending to the needs of the patients.

Ribavirin small-particle-aerosol treatment of influenza B virus infection

In a randomized double-blind trial of aerosolized ribavirin for the treatment of influenza B virus infection, no significant difference was found in the febrile course or symptom score of the ribavirin-treated versus placebo-treated patients. The apparent lack of efficacy in this study as compared with that in previous studies is unexplained.